1. Field of the Described Embodiments
The described embodiments relate generally to methods of injection molding. More particularly, methods of overmolding parts including delicate components are described.
2. Description of the Related Art
Injection molding is a manufacturing process where a part can be formed using a thermoplastic or a thermosetting plastic material. An initially solid material can be melted and forced into a mold cavity at a high pressure to ensure the melted material entirely fills the mold cavity. Then, the melted material can be allowed to cool such that it sets in a shape specified by the mold cavity configuration. An advantage of injection molding is that parts with complex geometries can be mass produced in a cost effective manner.
One type of injection molding is often referred to as overmolding or insert molding. In overmolding, a separate part can be placed into a mold in an injection molding unit and material can be injected around the separate part to form a new part. The material added around the initial part can be shaped according a mold cavity in the mold that surrounds the separate part. The separate part can have been formed using an injection molding process. However, the separate part can also have been formed using some other manufacturing process which is unrelated to injection molding.
In an overmolding process or an insert molding process, the mold cavity can be formed from a number of mold components. The mold components can be configured to interact such that they can be brought together to form the mold cavity and then separated. The mold components can be brought together to inject the mold material around a part initially placed into the mold. The mold components can be separated to allow a part to be initially placed into the mold cavity or a newly formed part including the part initially placed into the mold and the added material to be removed from the mold.
If the part initially placed in the mold is delicate, the positioning of the mold components relative to the part can be an issue. As part of the overmolding process or insert molding process, one or more of the mold components can be brought into contact with a portion of the part where the contact between the part and the mold components defines a portion of the overmolding shape. If the mold components contact the part with too much force, then the delicate part can be damaged. This is undesirable. However, if the mold components are not held against the delicate part with sufficient force, then the injection molding material can flow around the delicate part into areas in which it is not intended such that a molding flash is formed. The molding flash is undesirable because it may be necessary to remove the molding flash to allow the newly formed part to be used as it is intended. If removing the molding flash is too difficult, parts with an unacceptable molding flash can be discarded. However, discarding unsatisfactory parts requires an inspection methodology to determine, which parts are acceptable and which parts need to be discarded. This is also undesirable.
In view of the foregoing, there is a need for improved methods and apparatus for overmolding or insert molding on delicate parts.